A Stirling Cycle engine operates on a closed thermodynamic cycle in which one mass of gas is repeatedly expanded and compressed. Unlike an internal combustion engine, there are no valves, intake or exhaust ports, and no combustion in the cylinders. The engine therefore has very low noise output and can be dynamically balanced, thereby resulting in virtually no engine vibration. Little maintenance is required because the combustion products are kept away from the moving engine parts. A Stirling Cycle engine operates with externally heated cylinder heads. The burner of the present invention is thus particularly suited for providing the external heat source.
Desirably, a burner for a Stirling Cycle engine is able to burn different liquid and gaseous fuels. The burner should be quiet in operation otherwise the advantage of a quiet engine operation is lost. The burner desirably also has cool external surfaces and is sufficiently compact for mounting with the cylinder head of the engine. It goes without saying that the burner should also be efficient.
Examples of such burners can be seen in U.S. Pat. Nos. 4,352,269 (Dineen), 5,005,349 (Momose) and 5,590,526 (Cho). In Cho and Momose, either the inlet air or the exhaust air follows a passage that allows for heat exchange from the combustion chamber. Momose also permits some heat exchange between the exhaust gases and the inlet air, but only on one pass of the inlet air past the exhaust gas passageway. Dineen discloses a burner with an annular heat exchange means and an annular burner about the Stirling engine. The exhaust is centrally located at the top of the burner.
However these three burners have a limited amount of thermal connection between the inlet air and exhaust gases, reducing the efficiency of the heat exchange aspects of the burner. Also, with the burner disclosed in Dineen portions of the exterior of the burner will be hot as they are immediately adjacent the exhaust gas passageways of the burner.
A further difficulty of the disclosed burners is the complexity of manufacture or construction of the burner disclosed.
It is an object of the present invention to provide a burner for an external combustion engine which effectively addresses the question of efficient heat exchange with in the burner. It is a further object of the present invention to provide a burner which addresses the question of simplicity of manufacture.
A yet further object of the present invention is to provide a burner which meets or goes some way to achieving all or some of the aforementioned requirements or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.